1. Field of the Invention
The present invention relates to an expandable seal arrangement, and associated method, for sealing a gasket to an annular wall of a rigid structure.
2. Description of the Related Art
In underground pipe systems, it is often necessary to connect a pipe in a sealed manner within an opening in the wall of a rigid structure, such as a manhole riser or monolithic base, for example. Typically, a flexible elastomeric gasket is placed within the opening in the wall, followed by fitting an expansion ring against the interior surface of the gasket. Thereafter, a suitable expansion mechanism is used to radially expand the expansion ring and lock same in an expanded condition in which the gasket is sealingly compressed between the expansion ring and the opening in the wall of the structure. Thereafter, a pipe is inserted through the gasket, and one or more clamps are installed around a portion of the gasket which extends from the wall to sealingly compress the extending portion of the gasket between the clamps and the outer surface of the pipe. In this manner, a sealed connection is made between the pipe and the structure.
One known expansion ring includes a ratcheting engagement between overlapping ends of the ring. When the ends of the ring are forced in opposite directions from one another as the ring is radially expanded, ratchet teeth on the ring ends sequentially engage one another, wherein the expansion ring may be sequentially expanded in an incremental manner into multiple locked positions. A separate tool is used to engage the opposite ends of the expansion ring and to drive same apart from one another. Typically, such tools can be expensive, as same are specialized and designed for specific use only with a particular corresponding configuration of the expansion ring.
Although the foregoing expansion rings are effective, the expansion rings may only be expanded in designated increments which may not correspond to an ideal diameter of the expansion ring which is the most effective to sealingly compress the gasket between the expansion ring and an opening in the wall of the structure. For example, a suitable tool may be used to expand the expansion ring to an expanded, locked position in which the gasket is not compressed to its fullest extent between the expansion ring and the opening, yet further expansion of the expansion ring may not be possible because the gasket cannot be further compressed sufficiently to allow for expansion of the expansion ring to the next locked position.
What is needed is an expansion ring mechanism which is an improvement over the foregoing.